Area postrema mediation of physiological and behavioral effects of lithium chloride in the rat.

The area postrema (AP), a chemoreceptor trigger zone for nausea and vomiting, has been implicated in taste aversion conditioning with LiCl. In addition to taste aversion acquisition, the present studies indicate that a number of other responses to LiCl administration are eliminated by lesions of the AP. These include a behavioral response, 'lying-on-belly' as well as two physiological responses, delayed stomach emptying and hypothermia. These findings suggest that the area postrema is critically involved in the detection of LiCl and in a wide range of responses to this toxin. They also provide strong evidence that the failure to acquire conditioned taste aversions to LiCl-paired flavors after AP lesions can be attributed to the absence of a significant 'illness' response in lesioned animals.